This invention relates to an automatic isolator of blood plasma out of blood, by detecting the change of the transmittance of visible light at the border between the blood plasma layer and that of the blood cells.
Usually, blood plasma is isolated, using an isolator, for instance HEN-OL type isolator, after separation of the blood cells and blood plasma with a centrifugal machine.
The HEN-OL type isolator is described below. The HEN-OL type isolator has two boards on a base box; one of these boards is fixed at one end of the base box and stands vertically, the other is fastened to rotate around an axis at the same end of the base box.
The rotatable boards is always pushed by a plate spring (not illustrated) toward the vertical board.
A lever is fixed to the rotatable board at the opposite face to the vertical board.
The space between the two boards can be extended, by pushing down the lever and by fastening it at a hook, which protrudes out of the base box.
A bag, which is charged with blood and can be tightly sealing, can be suspended in this space between the two boards, using the hangers on top of the vertical board.
Releasing the lever, the blood bag will be pressed with the rotatable board into the dihendral space, so that the blood plasma can flow out from the blood bag through the tube.
Generally, there is a great difference in these bags as to quantity and in Hematcrik value, which will be abbreviated as H-value. In the conventional method, the blood plasma of a desired H-value, for example 70 or 90, is obtained, by stopping, with a top, the outflow of the blood plasma at the moment when it is visually observed that the border between the two layers reaches the outlet of the blood bag.
When one person operates many isolators of this type, the blood cells frequently intermingle with the isolated blood plasma, as a result of carelessness. Adding to this, the operation is so wearisome, that the number of isolators that can be operated by one person is restricted to two or three.
Blood plasma isolation is necessary within four hours after obtaining blood, for the purpose of producing a blood constituent drug, which request has recently remarkably increased. Now, an efficient isolator of blood plasma with a simplified method to detect the border mentioned above is expected to be developed.